Clark Fork River Operable Unit

The heavy metals (Cadmium, Copper, Zinc, and Lead) and arsenic in the Clark Fork River are from historic mining, milling and smelting processes linked to the Anaconda Company operations in Butte and Anaconda. The majority of the cleanup will occur along a 43-mile stretch of the river from Warm Springs in Anaconda/Deer Lodge County downstream to Garrison in Powell County. This is known as “Reach A.”

The Clark Fork River Operable Unit (CFR OU) is part of the Milltown Reservoir/Clark Fork River Superfund Site. The CFR OU includes the Clark Fork River from its headwaters near Warm Springs Creek to Milltown Reservoir, just east of Missoula.The primary sources of contamination are tailings mixed with soil in the streambanks and historic floodplain. These sources threaten human health and animal and plant life. The 2004 Record of Decision describes the cleanup approach, or Selected Remedy. In addition to the ROD, the NRDP developed a Restoration Plan to expedite the recovery time for injured aquatic and terrestrial resources in and along the Clark Fork River. To the extent practicable, the Restoration Plan will be combined with the Remedy to maximize the use of resources. The 2004 Record of Decision describes the cleanup approach, or Selected Remedy.

In 2008, 25 years after the state sued the Atlantic Richfield Co. for damage to natural resources, a settlement was reached and a federal judge signed the consent decree. The state received $123 million from ARCO for cleanup and restoration of mining pollution in the Clark Fork River Operable Unit.

The Montana Department of Environmental Quality (DEQ) and Montana Department of Justice, Natural Resource Damage Program (NRDP), with additional oversight from the U.S. Environmental Protection Agency (EPA) and National Parks Service (NPS) (for cleanup activities at the Grant-Kohrs Ranch operated by NPS) work collaboratively to design the remediation and restoration work.

In addition to the ROD, the NRDP developed a Restoration Plan to expedite the recovery time for injured aquatic and terrestrial resources in and along the Clark Fork River. To the extent practicable, the Restoration Plan will be combined with the Remedy to maximize the use of resources.

River Closure

Out of consideration for public safety, the Montana Fish & Wildlife Commission has closed 2.6-miles of the river through the Grant-Kohrs Ranch National Historic Site until October 2020. Closure signs will be posted upstream at Arrowstone Park, and just above the actual closure at the boundary of the Grant-Kohrs Ranch. Recognizing the impact to the community, DEQ and its contractors will work to reopen the river as quickly as possible, and to provide windows of recreation when safety considerations allow. Scheduled openings will be publicized well in advance to allow recreationists to take advantage of river access.

DEQ requested the river closure to protect the public. Temporary bridges to provide access to the west side of the river will not have clearance for boats or floaters, and portaging over active haul routes would be extremely hazardous, as heavy equipment operators have limited visibility. Only employees with extensive safety and communication training will be allowed on the construction site.

Karen Ogden

About Us

The Montana Department of Environmental Quality is charged with protecting a clean and healthy environment as guaranteed to our citizens by our State Constitution. Our ultimate goal is to protect public health and to maintain Montana's
high quality of life for current and future generations.